Organic electroluminescent materials and devices

ABSTRACT

Organic compounds containing indolocarbazoles as electron donor connected with electron acceptors such aza-triphenylene or dibenzoquinoxaline that can improve the performance of phosphorescent organic light emitting devices are disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/594,716, filed May 15, 2017, which claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application Ser. No. 62/341,207, filed May25, 2016, the entire contents of which are incorporated herein byreference.

FIELD

The present invention relates to organic materials containingindolocarbazoles as electron donor connected with electron acceptorssuch aza-triphenylene, and dibenzoquinoxaline suitable forphosphorescent organic light emitting diode (PHOLED) devices.

BACKGROUND

Opto-electronic devices that make use of organic materials are becomingincreasingly desirable for a number of reasons. Many of the materialsused to make such devices are relatively inexpensive, so organicopto-electronic devices have the potential for cost advantages overinorganic devices. In addition, the inherent properties of organicmaterials, such as their flexibility, may make them well suited forparticular applications such as fabrication on a flexible substrate.Examples of organic opto-electronic devices include organic lightemitting diodes/devices (OLEDs), organic phototransistors, organicphotovoltaic cells, and organic photodetectors. For OLEDs, the organicmaterials may have performance advantages over conventional materials.For example, the wavelength at which an organic emissive layer emitslight may generally be readily tuned with appropriate dopants.

OLEDs make use of thin organic films that emit light when voltage isapplied across the device. OLEDs are becoming an increasinglyinteresting technology for use in applications such as flat paneldisplays, illumination, and backlighting. Several OLED materials andconfigurations are described in U.S. Pat. Nos. 5,844,363, 6,303,238, and5,707,745, which are incorporated herein by reference in their entirety.

One application for phosphorescent emissive molecules is a full colordisplay. Industry standards for such a display call for pixels adaptedto emit particular colors, referred to as “saturated” colors. Inparticular, these standards call for saturated red, green, and bluepixels. Alternatively the OLED can be designed to emit white light. Inconventional liquid crystal displays emission from a white backlight isfiltered using absorption filters to produce red, green and blueemission. The same technique can also be used with OLEDs. The white OLEDcan be either a single EML device or a stack structure. Color may bemeasured using CIE coordinates, which are well known to the art.

One example of a green emissive molecule is tris(2-phenylpyridine)iridium, denoted Ir(ppy)₃, which has the following structure:

In this, and later figures herein, we depict the dative bond fromnitrogen to metal (here, Ir) as a straight line.

As used herein, the term “organic” includes polymeric materials as wellas small molecule organic materials that may be used to fabricateorganic opto-electronic devices. “Small molecule” refers to any organicmaterial that is not a polymer, and “small molecules” may actually bequite large Small molecules may include repeat units in somecircumstances. For example, using a long chain alkyl group as asubstituent does not remove a molecule from the “small molecule” class.Small molecules may also be incorporated into polymers, for example as apendent group on a polymer backbone or as a part of the backbone Smallmolecules may also serve as the core moiety of a dendrimer, whichconsists of a series of chemical shells built on the core moiety. Thecore moiety of a dendrimer may be a fluorescent or phosphorescent smallmolecule emitter. A dendrimer may be a “small molecule,” and it isbelieved that all dendrimers currently used in the field of OLEDs aresmall molecules.

As used herein, “top” means furthest away from the substrate, while“bottom” means closest to the substrate. Where a first layer isdescribed as “disposed over” or “deposited over” a second layer, thefirst layer is disposed further away from substrate. There may be otherlayers between the first and second layer, unless it is specified thatthe first layer is “in contact with” the second layer. For example, acathode may be described as “disposed over” or “deposited over” ananode, even though there are various organic layers in between.

As used herein, “solution processible” means capable of being dissolved,dispersed, or transported in and/or deposited from a liquid medium,either in solution or suspension form.

A ligand may be referred to as “photoactive” when it is believed thatthe ligand directly contributes to the photoactive properties of anemissive material. A ligand may be referred to as “ancillary” when it isbelieved that the ligand does not contribute to the photoactiveproperties of an emissive material, although an ancillary ligand mayalter the properties of a photoactive ligand.

As used herein, and as would be generally understood by one skilled inthe art, a first “Highest Occupied Molecular Orbital” (HOMO) or “LowestUnoccupied Molecular Orbital” (LUMO) energy level is “greater than” or“higher than” a second HOMO or LUMO energy level if the first energylevel is closer to the vacuum energy level. Since ionization potentials(IP) are measured as a negative energy relative to a vacuum level, ahigher HOMO energy level corresponds to an IP having a smaller absolutevalue (an IP that is less negative) Similarly, a higher LUMO energylevel corresponds to an electron affinity (EA) having a smaller absolutevalue (an EA that is less negative). On a conventional energy leveldiagram, with the vacuum level at the top, the LUMO energy level of amaterial is higher than the HOMO energy level of the same material. A“higher” HOMO or LUMO energy level appears closer to the top of such adiagram than a “lower” HOMO or LUMO energy level.

As used herein, and as would be generally understood by one skilled inthe art, a first work function is “greater than” or “higher than” asecond work function if the first work function has a higher absolutevalue. Because work functions are generally measured as negative numbersrelative to vacuum level, this means that a “higher” work function ismore negative. On a conventional energy level diagram, with the vacuumlevel at the top, a “higher” work function is illustrated as furtheraway from the vacuum level in the downward direction. Thus, thedefinitions of HOMO and LUMO energy levels follow a different conventionthan work functions.

More details on OLEDs, and the definitions described above, can be foundin U.S. Pat. No. 7,279,704, which is incorporated herein by reference inits entirety.

SUMMARY

Organic materials containing indolocarbazoles as electron donorconnected with electron acceptors such aza-triphenylene, anddibenzoquinoxaline are disclosed. Such materials are useful in PHOLEDdevices. These materials can enhance device performance in terms ofdevice lifetime, external quantum efficiency (EQE), and operationalvoltage

According to an aspect of the present disclosure, a compound having aformula

is disclosed. In Formula I, R¹ and R² each independently represent mono,di, tri, or tetra substitution, or no substitution; R³ represents mono,or di substitution, or no substitution; R⁵ represents mono, di, tri,tetra, or penta substitution, or no substitution; two of X¹ to X⁴ arecarbon, and the other two are nitrogen; L is a direct bond or an organiclinker; each R¹, R², R³, R⁴, and R⁵ are independently selected from thegroup consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl,heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl,cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl,carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl,sulfonyl, phosphino, and combinations thereof; and any adjacentsubstituents are optionally joined or fused into a ring.

According to another aspect of the present disclosure, an OLED isdisclosed where the OLED comprises: an anode; a cathode; and an organiclayer disposed between the anode and the cathode. The organic layercomprises a compound having a formula

In Formula I, R¹ and R² each independently represent mono, di, tri, ortetra substitution, or no substitution; R³ represents mono, or disubstitution, or no substitution; R⁵ represents mono, di, tri, tetra, orpenta substitution, or no substitution; two of X¹ to X⁴ are carbon, andthe other two are nitrogen; L is a direct bond or an organic linker;each R¹, R², R³, R⁴, and R⁵ are independently selected from the groupconsisting of hydrogen, deuterium, halide, alkyl, cycloalkyl,heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl,cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl,carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl,sulfonyl, phosphino, and combinations thereof; and any adjacentsubstituents are optionally joined or fused into a ring.

According to another aspect, a consumer product comprising an OLED isdisclosed where the OLED comprises: an anode; a cathode; and an organiclayer disposed between the anode and the cathode. The organic layercomprises a compound having a structure of Formula I.

According to another aspect, a formulation comprising a compound havinga structure of Formula I is also disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an organic light emitting device.

FIG. 2 shows an inverted organic light emitting device that does nothave a separate electron transport layer.

DETAILED DESCRIPTION

Generally, an OLED comprises at least one organic layer disposed betweenand electrically connected to an anode and a cathode. When a current isapplied, the anode injects holes and the cathode injects electrons intothe organic layer(s). The injected holes and electrons each migratetoward the oppositely charged electrode. When an electron and holelocalize on the same molecule, an “exciton,” which is a localizedelectron-hole pair having an excited energy state, is formed. Light isemitted when the exciton relaxes via a photoemissive mechanism. In somecases, the exciton may be localized on an excimer or an exciplex.Non-radiative mechanisms, such as thermal relaxation, may also occur,but are generally considered undesirable.

The initial OLEDs used emissive molecules that emitted light from theirsinglet states (“fluorescence”) as disclosed, for example, in U.S. Pat.No. 4,769,292, which is incorporated by reference in its entirety.Fluorescent emission generally occurs in a time frame of less than 10nanoseconds.

More recently, OLEDs having emissive materials that emit light fromtriplet states (“phosphorescence”) have been demonstrated. Baldo et al.,“Highly Efficient Phosphorescent Emission from OrganicElectroluminescent Devices,” Nature, vol. 395, 151-154, 1998;(“Baldo-I”) and Baldo et al., “Very high-efficiency green organiclight-emitting devices based on electrophosphorescence,” Appl. Phys.Lett., vol. 75, No. 3, 4-6 (1999) (“Baldo-II”), are incorporated byreference in their entireties. Phosphorescence is described in moredetail in U.S. Pat. No. 7,279,704 at cols. 5-6, which are incorporatedby reference.

FIG. 1 shows an organic light emitting device 100. The figures are notnecessarily drawn to scale. Device 100 may include a substrate 110, ananode 115, a hole injection layer 120, a hole transport layer 125, anelectron blocking layer 130, an emissive layer 135, a hole blockinglayer 140, an electron transport layer 145, an electron injection layer150, a protective layer 155, a cathode 160, and a barrier layer 170.Cathode 160 is a compound cathode having a first conductive layer 162and a second conductive layer 164. Device 100 may be fabricated bydepositing the layers described, in order. The properties and functionsof these various layers, as well as example materials, are described inmore detail in U.S. Pat. No. 7,279,704 at cols. 6-10, which areincorporated by reference.

More examples for each of these layers are available. For example, aflexible and transparent substrate-anode combination is disclosed inU.S. Pat. No. 5,844,363, which is incorporated by reference in itsentirety. An example of a p-doped hole transport layer is m-MTDATA dopedwith F₄-TCNQ at a molar ratio of 50:1, as disclosed in U.S. PatentApplication Publication No. 2003/0230980, which is incorporated byreference in its entirety. Examples of emissive and host materials aredisclosed in U.S. Pat. No. 6,303,238 to Thompson et al., which isincorporated by reference in its entirety. An example of an n-dopedelectron transport layer is BPhen doped with Li at a molar ratio of 1:1,as disclosed in U.S. Patent Application Publication No. 2003/0230980,which is incorporated by reference in its entirety. U.S. Pat. Nos.5,703,436 and 5,707,745, which are incorporated by reference in theirentireties, disclose examples of cathodes including compound cathodeshaving a thin layer of metal such as Mg:Ag with an overlyingtransparent, electrically-conductive, sputter-deposited ITO layer. Thetheory and use of blocking layers is described in more detail in U.S.Pat. No. 6,097,147 and U.S. Patent Application Publication No.2003/0230980, which are incorporated by reference in their entireties.Examples of injection layers are provided in U.S. Patent ApplicationPublication No. 2004/0174116, which is incorporated by reference in itsentirety. A description of protective layers may be found in U.S. PatentApplication Publication No. 2004/0174116, which is incorporated byreference in its entirety.

FIG. 2 shows an inverted OLED 200. The device includes a substrate 210,a cathode 215, an emissive layer 220, a hole transport layer 225, and ananode 230. Device 200 may be fabricated by depositing the layersdescribed, in order. Because the most common OLED configuration has acathode disposed over the anode, and device 200 has cathode 215 disposedunder anode 230, device 200 may be referred to as an “inverted” OLED.Materials similar to those described with respect to device 100 may beused in the corresponding layers of device 200. FIG. 2 provides oneexample of how some layers may be omitted from the structure of device100.

The simple layered structure illustrated in FIGS. 1 and 2 is provided byway of non-limiting example, and it is understood that embodiments ofthe invention may be used in connection with a wide variety of otherstructures. The specific materials and structures described areexemplary in nature, and other materials and structures may be used.Functional OLEDs may be achieved by combining the various layersdescribed in different ways, or layers may be omitted entirely, based ondesign, performance, and cost factors. Other layers not specificallydescribed may also be included. Materials other than those specificallydescribed may be used. Although many of the examples provided hereindescribe various layers as comprising a single material, it isunderstood that combinations of materials, such as a mixture of host anddopant, or more generally a mixture, may be used. Also, the layers mayhave various sublayers. The names given to the various layers herein arenot intended to be strictly limiting. For example, in device 200, holetransport layer 225 transports holes and injects holes into emissivelayer 220, and may be described as a hole transport layer or a holeinjection layer. In one embodiment, an OLED may be described as havingan “organic layer” disposed between a cathode and an anode. This organiclayer may comprise a single layer, or may further comprise multiplelayers of different organic materials as described, for example, withrespect to FIGS. 1 and 2 .

Structures and materials not specifically described may also be used,such as OLEDs comprised of polymeric materials (PLEDs) such as disclosedin U.S. Pat. No. 5,247,190 to Friend et al., which is incorporated byreference in its entirety. By way of further example, OLEDs having asingle organic layer may be used. OLEDs may be stacked, for example asdescribed in U.S. Pat. No. 5,707,745 to Forrest et al, which isincorporated by reference in its entirety. The OLED structure maydeviate from the simple layered structure illustrated in FIGS. 1 and 2 .For example, the substrate may include an angled reflective surface toimprove out-coupling, such as a mesa structure as described in U.S. Pat.No. 6,091,195 to Forrest et al., and/or a pit structure as described inU.S. Pat. No. 5,834,893 to Bulovic et al., which are incorporated byreference in their entireties.

Unless otherwise specified, any of the layers of the various embodimentsmay be deposited by any suitable method. For the organic layers,preferred methods include thermal evaporation, ink-jet, such asdescribed in U.S. Pat. Nos. 6,013,982 and 6,087,196, which areincorporated by reference in their entireties, organic vapor phasedeposition (OVPD), such as described in U.S. Pat. No. 6,337,102 toForrest et al., which is incorporated by reference in its entirety, anddeposition by organic vapor jet printing (OVJP), such as described inU.S. Pat. No. 7,431,968, which is incorporated by reference in itsentirety. Other suitable deposition methods include spin coating andother solution based processes. Solution based processes are preferablycarried out in nitrogen or an inert atmosphere. For the other layers,preferred methods include thermal evaporation. Preferred patterningmethods include deposition through a mask, cold welding such asdescribed in U.S. Pat. Nos. 6,294,398 and 6,468,819, which areincorporated by reference in their entireties, and patterning associatedwith some of the deposition methods such as ink jet and OVJP. Othermethods may also be used. The materials to be deposited may be modifiedto make them compatible with a particular deposition method. Forexample, substituents such as alkyl and aryl groups, branched orunbranched, and preferably containing at least 3 carbons, may be used insmall molecules to enhance their ability to undergo solution processing.Substituents having 20 carbons or more may be used, and 3-20 carbons isa preferred range. Materials with asymmetric structures may have bettersolution processability than those having symmetric structures, becauseasymmetric materials may have a lower tendency to recrystallize.Dendrimer substituents may be used to enhance the ability of smallmolecules to undergo solution processing.

Devices fabricated in accordance with embodiments of the presentinvention may further optionally comprise a barrier layer. One purposeof the barrier layer is to protect the electrodes and organic layersfrom damaging exposure to harmful species in the environment includingmoisture, vapor and/or gases, etc. The barrier layer may be depositedover, under or next to a substrate, an electrode, or over any otherparts of a device including an edge. The barrier layer may comprise asingle layer, or multiple layers. The barrier layer may be formed byvarious known chemical vapor deposition techniques and may includecompositions having a single phase as well as compositions havingmultiple phases. Any suitable material or combination of materials maybe used for the barrier layer. The barrier layer may incorporate aninorganic or an organic compound or both. The preferred barrier layercomprises a mixture of a polymeric material and a non-polymeric materialas described in U.S. Pat. No. 7,968,146, PCT Pat. Application Nos.PCT/US2007/023098 and PCT/US2009/042829, which are herein incorporatedby reference in their entireties. To be considered a “mixture”, theaforesaid polymeric and non-polymeric materials comprising the barrierlayer should be deposited under the same reaction conditions and/or atthe same time. The weight ratio of polymeric to non-polymeric materialmay be in the range of 95:5 to 5:95. The polymeric material and thenon-polymeric material may be created from the same precursor material.In one example, the mixture of a polymeric material and a non-polymericmaterial consists essentially of polymeric silicon and inorganicsilicon.

Devices fabricated in accordance with embodiments of the invention canbe incorporated into a wide variety of electronic component modules (orunits) that can be incorporated into a variety of electronic products orintermediate components. Examples of such electronic products orintermediate components include display screens, lighting devices suchas discrete light source devices or lighting panels, etc. that can beutilized by the end-user product manufacturers. Such electroniccomponent modules can optionally include the driving electronics and/orpower source(s). Devices fabricated in accordance with embodiments ofthe invention can be incorporated into a wide variety of consumerproducts that have one or more of the electronic component modules (orunits) incorporated therein. Such consumer products would include anykind of products that include one or more light source(s) and/or one ormore of some type of visual displays. Some examples of such consumerproducts include flat panel displays, computer monitors, medicalmonitors, televisions, billboards, lights for interior or exteriorillumination and/or signaling, heads-up displays, fully or partiallytransparent displays, flexible displays, laser printers, telephones,cell phones, tablets, phablets, personal digital assistants (PDAs),wearable devices, laptop computers, digital cameras, camcorders,viewfinders, micro-displays (displays that are less than 2 inchesdiagonal), 3-D displays, virtual reality or augmented reality displays,vehicles, video walls comprising multiple displays tiled together,theater or stadium screen, and a sign. Various control mechanisms may beused to control devices fabricated in accordance with the presentinvention, including passive matrix and active matrix. Many of thedevices are intended for use in a temperature range comfortable tohumans, such as 18 degrees C. to 30 degrees C., and more preferably atroom temperature (20-25 degrees C.), but could be used outside thistemperature range, for example, from −40 degree C. to +80 degree C.

The materials and structures described herein may have applications indevices other than OLEDs. For example, other optoelectronic devices suchas organic solar cells and organic photodetectors may employ thematerials and structures. More generally, organic devices, such asorganic transistors, may employ the materials and structures.

The term “halo,” “halogen,” or “halide” as used herein includesfluorine, chlorine, bromine, and iodine.

The term “alkyl” as used herein contemplates both straight and branchedchain alkyl radicals. Preferred alkyl groups are those containing fromone to fifteen carbon atoms and includes methyl, ethyl, propyl,1-methylethyl, butyl, 1-methylpropyl, 2-methylpropyl, pentyl,1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1,1-dimethylpropyl,1,2-dimethylpropyl, 2,2-dimethylpropyl, and the like. Additionally, thealkyl group may be optionally substituted.

The term “cycloalkyl” as used herein contemplates cyclic alkyl radicals.Preferred cycloalkyl groups are those containing 3 to 10 ring carbonatoms and includes cyclopropyl, cyclopentyl, cyclohexyl, adamantyl, andthe like. Additionally, the cycloalkyl group may be optionallysubstituted.

The term “alkenyl” as used herein contemplates both straight andbranched chain alkene radicals. Preferred alkenyl groups are thosecontaining two to fifteen carbon atoms. Additionally, the alkenyl groupmay be optionally substituted.

The term “alkynyl” as used herein contemplates both straight andbranched chain alkyne radicals. Preferred alkynyl groups are thosecontaining two to fifteen carbon atoms. Additionally, the alkynyl groupmay be optionally substituted.

The terms “aralkyl” or “arylalkyl” as used herein are usedinterchangeably and contemplate an alkyl group that has as a substituentan aromatic group. Additionally, the aralkyl group may be optionallysubstituted.

The term “heterocyclic group” as used herein contemplates aromatic andnon-aromatic cyclic radicals. Hetero-aromatic cyclic radicals also meansheteroaryl. Preferred hetero-non-aromatic cyclic groups are thosecontaining 3 to 7 ring atoms which includes at least one hetero atom,and includes cyclic amines such as morpholino, piperdino, pyrrolidino,and the like, and cyclic ethers, such as tetrahydrofuran,tetrahydropyran, and the like. Additionally, the heterocyclic group maybe optionally substituted.

The term “aryl” or “aromatic group” as used herein contemplatessingle-ring groups and polycyclic ring systems. The polycyclic rings mayhave two or more rings in which two carbons are common to two adjoiningrings (the rings are “fused”) wherein at least one of the rings isaromatic, e.g., the other rings can be cycloalkyls, cycloalkenyls, aryl,heterocycles, and/or heteroaryls. Preferred aryl groups are thosecontaining six to thirty carbon atoms, preferably six to twenty carbonatoms, more preferably six to twelve carbon atoms. Especially preferredis an aryl group having six carbons, ten carbons or twelve carbons.Suitable aryl groups include phenyl, biphenyl, triphenyl, triphenylene,tetraphenylene, naphthalene, anthracene, phenalene, phenanthrene,fluorene, pyrene, chrysene, perylene, and azulene, preferably phenyl,biphenyl, triphenyl, triphenylene, fluorene, and naphthalene.Additionally, the aryl group may be optionally substituted.

The term “heteroaryl” as used herein contemplates single-ringhetero-aromatic groups that may include from one to five heteroatoms.The term heteroaryl also includes polycyclic hetero-aromatic systemshaving two or more rings in which two atoms are common to two adjoiningrings (the rings are “fused”) wherein at least one of the rings is aheteroaryl, e.g., the other rings can be cycloalkyls, cycloalkenyls,aryl, heterocycles, and/or heteroaryls. Preferred heteroaryl groups arethose containing three to thirty carbon atoms, preferably three totwenty carbon atoms, more preferably three to twelve carbon atoms.Suitable heteroaryl groups include dibenzothiophene, dibenzofuran,dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene,benzoselenophene, carbazole, indolocarbazole, pyridylindole,pyrrolodipyridine, pyrazole, imidazole, triazole, oxazole, thiazole,oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine,pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine,indole, benzimidazole, indazole, indoxazine, benzoxazole, benzisoxazole,benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline,quinoxaline, naphthyridine, phthalazine, pteridine, xanthene, acridine,phenazine, phenothiazine, phenoxazine, benzofuropyridine,furodipyridine, benzothienopyridine, thienodipyridine,benzoselenophenopyridine, and selenophenodipyridine, preferablydibenzothiophene, dibenzofuran, dibenzoselenophene, carbazole,indolocarbazole, imidazole, pyridine, triazine, benzimidazole,1,2-azaborine, 1,3-azaborine, 1,4-azaborine, borazine, and aza-analogsthereof. Additionally, the heteroaryl group may be optionallysubstituted.

The alkyl, cycloalkyl, alkenyl, alkynyl, aralkyl, heterocyclic group,aryl, and heteroaryl may be unsubstituted or may be substituted with oneor more substituents selected from the group consisting of deuterium,halogen, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy,amino, cyclic amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl,alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ether,ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, andcombinations thereof.

As used herein, “substituted” indicates that a substituent other than His bonded to the relevant position, such as carbon. Thus, for example,where R¹ is mono-substituted, then one R¹ must be other than H.Similarly, where R¹ is di-substituted, then two of R¹ must be other thanH. Similarly, where R¹ is unsubstituted, R¹ is hydrogen for allavailable positions.

The “aza” designation in the fragments described herein, i.e.aza-dibenzofuran, aza-dibenzothiophene, etc. means that one or more ofthe C—H groups in the respective fragment can be replaced by a nitrogenatom, for example, and without any limitation, azatriphenyleneencompasses both dibenzo[f,h]quinoxaline and dibenzo[f,h]quinoline. Oneof ordinary skill in the art can readily envision other nitrogen analogsof the aza-derivatives described above, and all such analogs areintended to be encompassed by the terms as set forth herein.

It is to be understood that when a molecular fragment is described asbeing a substituent or otherwise attached to another moiety, its namemay be written as if it were a fragment (e.g. phenyl, phenylene,naphthyl, dibenzofuryl) or as if it were the whole molecule (e.g.benzene, naphthalene, dibenzofuran). As used herein, these differentways of designating a substituent or attached fragment are considered tobe equivalent.

According to an aspect of the present disclosure, a compound having aformula

is disclosed. In Formula I, R¹ and R² each independently represent mono,di, tri, or tetra substitution, or no substitution; R³ represents mono,or di substitution, or no substitution; R⁵ represents mono, di, tri,tetra, or penta substitution, or no substitution; two of X¹ to X⁴ arecarbon, and the other two are nitrogen; L is a direct bond or an organiclinker; each R¹, R², R³, R⁴, and R⁵ are independently selected from thegroup consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl,heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl,cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl,carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl,sulfonyl, phosphino, and combinations thereof; and wherein any adjacentsubstituents are optionally joined or fused into a ring.

In some embodiments of the compound of Formula I, the compound isselected from the group consisting of:

wherein R⁶ and R⁷ each independently represent mono, di, tri, or tetrasubstitution, or no substitution; each R⁶ and R⁷ are independentlyselected from the group consisting of hydrogen, deuterium, halide,alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino,silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl,acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl,sulfinyl, sulfonyl, phosphino, and combinations thereof; and anyadjacent substituents of R⁶ and R⁷ are optionally joined or fused into aring.

In some embodiments of the compound of Formula I, each R¹, R², R³, R⁴,and R⁵ are independently selected from the group consisting of aryl,substituted aryl, heteroaryl, and substituted heteroaryl.

In some embodiments of the compound of Formula I, L is a direct bond. Insome embodiments, L is an organic linker selected from the groupconsisting of aryl, substituted aryl, heteroaryl, substitutedheteroaryl, amino, silyl, and combination thereof.

In some embodiments of the compound of Formula I, R³ is hydrogen. Insome embodiments, R¹ and R² are hydrogen.

In some embodiments of the compound of Formula I, the compound isselected from the group consisting of:

According to an aspect of the present disclosure, an OLED comprising ananode; a cathode; and an organic layer disposed between the anode andthe cathode is disclosed. The organic layer comprises a compound havinga formula

wherein R¹ and R² each independently represent mono, di, tri, or tetrasubstitution, or no substitution; wherein R³ represents mono, or disubstitution, or no substitution; wherein R⁵ represents mono, di, tri,tetra, or penta substitution, or no substitution; wherein two of X¹ toX⁴ are carbon, and the other two are nitrogen; wherein L is a directbond or an organic linker; wherein each R¹, R², R³, R⁴, and R⁵ areindependently selected from the group consisting of hydrogen, deuterium,halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy,amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl,heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof; and wherein any adjacent substituents are optionally joined orfused into a ring.

In some embodiments of the OLED, the organic layer is an emissive layerand the compound of Formula I is a host. In some embodiments of theOLED, the organic layer further comprises a phosphorescent emissivedopant; wherein the emissive dopant is a transition metal complex havingat least one ligand or part of the ligand if the ligand is more thanbidentate, selected from the group consisting of:

wherein each X¹ to X¹³ are independently selected from the groupconsisting of carbon and nitrogen;

wherein X is selected from the group consisting of BR′, NR′, PR′, O, S,Se, C═O, S═O, SO₂, CR′R″, SiR′R″, and GeR′R″;

wherein R′ and R″ are optionally fused or joined to form a ring;

wherein each R_(a), R_(b), R_(c), and R_(d) may represent from monosubstitution to the possible maximum number of substitution, or nosubstitution;

wherein R′, R″, R_(a), R_(b), R_(c), and R_(d) are each independentlyselected from the group consisting of hydrogen, deuterium, halide,alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino,silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl,acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl,sulfinyl, sulfonyl, phosphino, and combinations thereof; and

-   -   wherein any two adjacent substituents of R_(a), R_(b), R_(c),        and R_(d) are optionally fused or joined to form a ring or form        a multidentate ligand.

In some embodiments of the OLED, the organic layer is a charge carrierblocking layer and the compound of Formula I is a charge carrierblocking material in the organic layer.

In some embodiments of the OLED, the organic layer is a charge carriertransporting layer and the compound of Formula I is a charge carriertransporting material in the organic layer.

In some embodiments of the OLED, the organic layer is an emissive layerand the compound of Formula I is an emitter.

In some embodiments of the OLED, the OLED emits a luminescent radiationat room temperature when a voltage is applied across the organic lightemitting device, and wherein the luminescent radiation comprises adelayed fluorescence process.

In some embodiments of the OLED, the emissive layer further comprises ahost material. In some embodiments, the emissive layer further comprisesa first phosphorescent emitting material. In some embodiments, theemissive layer further comprises a second phosphorescent emittingmaterial.

In some embodiments, the OLED emits a white light at room temperaturewhen a voltage is applied across the organic light emitting device.

In some embodiments of the OLED, the compound comprising a structureaccording to Formula I emits a blue light with a peak wavelength ofabout 400 nm to about 500 nm. In some embodiments, the compoundcomprising a structure according to Formula I emits a yellow light witha peak wavelength of about 530 nm to about 580 nm.

According to another aspect, a consumer product comprising an OLED isdisclosed where the OLED comprises: an anode; a cathode; and an organiclayer, disposed between the anode and the cathode, comprising a compoundhaving a formula

wherein R¹ and R² each independently represent mono, di, tri, or tetrasubstitution, or no substitution;

wherein R³ represents mono, or di substitution, or no substitution;

wherein R⁵ represents mono, di, tri, tetra, or penta substitution, or nosubstitution;

wherein two of X¹ to X⁴ are carbon, and the other two are nitrogen;

wherein L is a direct bond or an organic linker;

wherein each R¹, R², R³, R⁴, and R⁵ are independently selected from thegroup consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl,heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl,cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl,carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl,sulfonyl, phosphino, and combinations thereof; and

wherein any adjacent substituents are optionally joined or fused into aring.

In some embodiments, the consumer product is selected from the groupconsisting of flat panel displays, computer monitors, medical monitors,televisions, billboards, lights for interior or exterior illuminationand/or signaling, heads-up displays, fully or partially transparentdisplays, flexible displays, laser printers, telephones, mobile phones,tablets, phablets, personal digital assistants (PDAs), wearable devices,laptop computers, digital cameras, camcorders, viewfinders,micro-displays, 3-D displays, virtual reality or augmented realitydisplays, vehicles, video walls comprising multiple displays tiledtogether, theater or stadium screen, and a sign.

According to another aspect, a formulation comprising a compound havingFormula I is disclosed.

SYNTHESIS EXAMPLES Synthesis of Compound Cmp D-2

A 3-neck round flask was charged with5-phenyl-5,8-dihydroindolo[2,3-c]carbazole (5 g, 15.04 mmol). AnhydrousDMF (100 ml) was added into it. To this clear solution, sodium hydride(1.203 g, 30.1 mmol) was added. Resulting mixture was stirred for 1 hr.4-([1,1′-biphenyl]-4-yl)-2-chloroquinazoline (5.72 g, 18.05 mmol) wasthen added and resulting mixture was stirred at room temperatureovernight. The reaction mixture was quenched with ice/cold H₂O (1.5 L).Resulting mixture was stirred for 30 min. Yellow solid was filtered andwashed with H₂O (1 L). Solid was dried, suspended in toluene (500 mL),heated and stirred for 30 min. This suspension was again warmed andfiltered. Solid was washed with toluene & passed through a plug ofsilica. This compound was suspended in DCM (100 mL) & acetone (250 mL).This suspension was heated & then stirred at room temperature overnight.It was filtered and washed with acetone (200 mL). This solid was driedunder vacuum to afford5-(4-([1,1′-biphenyl]-4-yl)quinazolin-2-yl)-8-phenyl-5,8-dihydroindolo[2,3-c]carbazole(7.1 g, 77% yield, HPLC 99.99%). NMR confirmed the structure.

Synthesis of Compound Cmp D-17

A 3-neck round flask was charged with5-phenyl-5,8-dihydroindolo[2,3-c]carbazole (5 g, 15.04 mmol). AnhydrousDMF (100 mL) was added into it. To this clear solution, sodium hydride(1.203 g, 30.1 mmol) was added. The reaction mixture becameheterogeneous. It was stirred for 1 hr then2-chloro-4-(naphthalen-2-yl)quinazoline (5.25 g, 18.05 mmol) was addedinto the reaction mixture. The reaction mixture turned brown. Theresulting mixture was stirred at room temperature for overnight.Reaction mixture was quenched with ice-cold H₂O (˜1 L). Resultingmixture was stirred for 30 min. Yellow solid was filtered and washedwith H₂O. Solid was then triturated with hot toluene. Solid was thenpassed through a plug of silica eluting with toluene. Upon drying5-(4-(naphthalen-2-yl)quinazolin-2-yl)-8-phenyl-5,8-dihydroindolo[2,3-c]carbazole(7 g, 11.93 mmol, 79% yield) was obtained as a yellow solid with 99.98%HPLC purity. NMR confirmed the structure.

Synthesis of Compound Cmp D-64

To a 250 mL round flask equipped with a condenser, stir bar, andthermocouple were added 5-phenyl-5,8-dihydroindolo[2,3-c]carbazole (5.00g, 15.04 mmol), 4-([1,1′-biphenyl]-4-yl)-2-(4-chlorophenyl)quinazoline(7.09 g, 18.05 mmol), sodium tert-butoxide (2.89 g, 30.1 mmol), andXylene (75 ml) (bubbled with nitrogen for 20 min) under nitrogen. Thenwas added Pd₂(dba)₃ (0.826 g, 0.903 mmol) anddicyclohexyl(2′,6′-dimethoxy-[1,1′-biphenyl]-2-yl)phosphane (0.741 g,1.805 mmol). The reaction mixture was heated to reflux (129° C.) for 4hr. The reaction appeared complete by TLC analysis at 3 hr. The darkbrown reaction mixture was allowed to cool to room temperature. Themixture was then filtered through a short pad of Celite and washedthrough with CH₂Cl₂ (˜200 mL). After concentrating the filtrate thecrude product was obtained as a dark brown oil (˜20 g). The crudeproduct was triturated with acetone (250 mL). A yellow-green solid wasobtained and was triturated with acetone again to give a yellow-greensolid. The sample was dissolved in hot toluene and was filtered througha pad of celite while warm. The celite was washed with toluene. Thefiltrate was concentrated (10 g) and subjected to chromatography onsilica gel (100 g). The fractions collected with 30-50% DCM/heptane werecombined and concentrated. The HPLC purity was 98.89%. The material wasdissolved in 300 mL of hot DCM. No solid formed upon cooling to RT sothe product was precipitated with MeOH (220 mL). The resulting yellowsolid was collected via filtration and analyzed via HPLC (99.90%). Theproduct was dried on high vac for 5 hr. ¹H NMR was consistent withproduct and 7.67 g was isolated (73.9% yield).

Synthesis of Compound Cmp D-70

In a 250 mL flask, to a solution of5-(naphthalen-2-yl)-5,8-dihydroindolo[2,3-c]carbazole (3.82 g, 10.0mmol) in anhydrous DMF (80 ml) was added sodium hydride (0.800 g, 20.00mmol), slowly. The suspension was stirred at room temperature for 1 hrand then 2-chloro-4-(naphthalen-2-yl)quinazoline (3.20 g, 11.00 mmol)was slowly added to the mixture. The mixture was stirred at roomtemperature overnight. The reaction was assessed by TLC, which indicated˜20% of unreacted starting material. Additional NaH (0.200 g, 5.0 mmol)was added to the reaction and after stirring at room temperature for 1hr, quinazoline intermediate (0.800 g, 2.75 mmol) was added and thereaction stirred at room temperature for 6 hr. After reactioncompletion, the mixture was poured over ice-water and the resultingsuspension was stirred at room temperature for 1 hr. The solid was thenfiltered, collected, and triturated with a mixture ofMeOH—CH₂Cl₂-acetone to provide5-(naphthalen-2-yl)-8-(4-(naphthalen-2-yl)quinazolin-2-yl)-5,8-dihydroindolo[2,3-c]carbazole(5.85 g, 9.13 mmol, 91% yield) as a yellow solid with 99.34% HPLCpurity. NMR confirmed the structure.

Synthesis of Compound Cmp D-82

A 250 mL round flask was fitted with a stir bar, N₂-inlet, and two septaand flushed with nitrogen for 30 min.5-phenyl-5,8-dihydroindolo[2,3-c]carbazole (3.63 g, 10.92 mmol) was thenadded, followed by anhydrous DMF (73 mL). sodium hydride (0.874 g, 21.84mmol) was added and the reaction was stirred for 1 hr before adding4-([1,1′-biphenyl]-4-yl)-2-chloro-6-phenylquinazoline (5.15 g, 13.10mmol) and rinsing it in with anhydrous DMF (10 mL) in two 5 mL portions.The reaction was stirred at room temperature overnight. TLC (thin-layerchromatography) showed excellent conversion, and the reaction wasquenched by pouring into ice/water (1 L) with stirring. The resultingsuspension was filtered to give an orange solid. The orange solid (30 g)was dissolved in DCM and run through a silica plug (150 g silica) usingDCM as eluent to give5-(4-([1,1′-biphenyl]-4-yl)-6-phenylquinazolin-2-yl)-8-phenyl-5,8-dihydroindolo[2,3-c]carbazolewith some overlap (7.1 g, 90% yield, HPLC 95%). NMR confirmed thestructure.

Device Examples

All example devices were fabricated by high vacuum (<10⁻⁷ Torr) thermalevaporation. The anode electrode was 1,150 Å of indium tin oxide (ITO).The cathode consisted of 10 Å of Liq (8-hydroxyquinoline lithium)followed by 1,000 Å of Al. All devices were encapsulated with a glasslid sealed with an epoxy resin in a nitrogen glove box (<1 ppm of H₂Oand O₂) immediately after fabrication with a moisture getterincorporated inside the package. The organic stack of the deviceexamples consisted of sequentially, from the ITO Surface: 100 Å ofHAT-CN as the hole injection layer (HIL); 450 Å of HTM as a holetransporting layer (HTL); emissive layer (EML) with thickness 400 Å.Emissive layer containing Host: Red Emitter (RD) 3% by weight. 350 Å ofLiq (8-hydroxyquinoline lithium) doped with 40% of ETM as the ETL. Hostcompounds Cmp D-17 and Cmp D-64 were used as Examples 1 and 2, CompoundC-Host as an comparative example CE1. Device structure is shown in Table1 below.

The chemical structures of the device materials are shown below:

Upon fabrication, the devices have been measured EL, JVL and lifetestedat DC 80 mA/cm². LT95 at 1,000 nits was calculated from 80 mA/cm2 LTdata assuming acceleration factor 2. Device performance is shown inTable 2 below.

Table 1. Device Example Layer Structure

TABLE 1 Device example layer structure Thickness Layer Material [Å]Anode ITO 1,150 HIL HAT-CN 100 HTL HTM 450 Red EML Host: RD 3% 400 ETLLiq: ETM 40% 350 EIL Liq 10 Cathode Al 1,000

TABLE 2 Device performance of Example 1 and CE1 At 1,000 nits VoltageRelative Relative Relative Relative Example Host [V] LE EQE PE LT 95%Example 1 Cmp D-17 3.6 1.9 1.9 2.0 66,000 Example 2 Cmp D-64 3.3 1.7 1.71.9 14,000 CE 1 C1-Host 3.7 1.0 1.0 1.0 1

The device data shows that the inventive compounds Cmp D-17 and Cmp D-64have superior performance vs comparative compound C-Host in voltage,external quantum efficiency (EQE), luminous efficiency (LE), powerefficiency (PE) and the lifetime (LT95). The synthesis of comparativeexample of C2-Host failed due to steric hindrance, which indicates thatC2-Host is highly unstable. The above experimental results indicate thatred hosts containing 5,8-dihydroindolo[2,3-c]carbazole have betterdevice performance than red hosts containing other indolocarbazoles suchas 11,12-dihydroindolo[2,3-a]carbazole.

Combination with Other Materials

The materials described herein as useful for a particular layer in anorganic light emitting device may be used in combination with a widevariety of other materials present in the device. For example, emissivedopants disclosed herein may be used in conjunction with a wide varietyof hosts, transport layers, blocking layers, injection layers,electrodes and other layers that may be present. The materials describedor referred to below are non-limiting examples of materials that may beuseful in combination with the compounds disclosed herein, and one ofskill in the art can readily consult the literature to identify othermaterials that may be useful in combination.

Conductivity Dopants:

A charge transport layer can be doped with conductivity dopants tosubstantially alter its density of charge carriers, which will in turnalter its conductivity. The conductivity is increased by generatingcharge carriers in the matrix material, and depending on the type ofdopant, a change in the Fermi level of the semiconductor may also beachieved. Hole-transporting layer can be doped by p-type conductivitydopants and n-type conductivity dopants are used in theelectron-transporting layer.

Non-limiting examples of the conductivity dopants that may be used in anOLED in combination with materials disclosed herein are exemplifiedbelow together with references that disclose those materials:EP01617493, EP01968131, EP2020694, EP2684932, US20050139810,US20070160905, US20090167167, US2010288362, WO06081780, WO2009003455,WO2009008277, WO2009011327, WO2014009310, US2007252140, US2015060804 andUS2012146012.

HIL/HTL:

A hole injecting/transporting material to be used in the presentinvention is not particularly limited, and any compound may be used aslong as the compound is typically used as a hole injecting/transportingmaterial. Examples of the material include, but are not limited to: aphthalocyanine or porphyrin derivative; an aromatic amine derivative; anindolocarbazole derivative; a polymer containing fluorohydrocarbon; apolymer with conductivity dopants; a conducting polymer, such asPEDOT/PSS; a self-assembly monomer derived from compounds such asphosphonic acid and silane derivatives; a metal oxide derivative, suchas MoO_(x); a p-type semiconducting organic compound, such as1,4,5,8,9,12-Hexaazatriphenylenehexacarbonitrile; a metal complex, and across-linkable compounds.

Examples of aromatic amine derivatives used in HIL or HTL include, butare not limited to the following general structures:

Each of Ar¹ to Ar⁹ is selected from the group consisting of aromatichydrocarbon cyclic compounds such as benzene, biphenyl, triphenyl,triphenylene, naphthalene, anthracene, phenalene, phenanthrene,fluorene, pyrene, chrysene, perylene, and azulene; the group consistingof aromatic heterocyclic compounds such as dibenzothiophene,dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran,benzothiophene, benzoselenophene, carbazole, indolocarbazole,pyridylindole, pyrrolodipyridine, pyrazole, imidazole, triazole,oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole,pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine,oxathiazine, oxadiazine, indole, benzimidazole, indazole, indoxazine,benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline,cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine,pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine,benzofuropyridine, furodipyridine, benzothienopyridine,thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine;and the group consisting of 2 to 10 cyclic structural units which aregroups of the same type or different types selected from the aromatichydrocarbon cyclic group and the aromatic heterocyclic group and arebonded to each other directly or via at least one of oxygen atom,nitrogen atom, sulfur atom, silicon atom, phosphorus atom, boron atom,chain structural unit and the aliphatic cyclic group. Each Ar may beunsubstituted or may be substituted by a substituent selected from thegroup consisting of deuterium, halide, alkyl, cycloalkyl, heteroalkyl,arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl,heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylicacids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl,phosphino, and combinations thereof.

In one aspect, Ar¹ to Ar⁹ is independently selected from the groupconsisting of:

wherein k is an integer from 1 to 20; X¹⁰¹ to X¹⁰⁸ is C (including CH)or N; Z¹⁰¹ is NAr¹, O, or S; Ar¹ has the same group defined above.

Examples of metal complexes used in HIL or HTL include, but are notlimited to the following general formula:

wherein Met is a metal, which can have an atomic weight greater than 40;(Y¹⁰¹-Y¹⁰²) is a bidentate ligand, Y¹⁰¹ and Y¹⁰² are independentlyselected from C, N, O, P, and S; L¹⁰¹ is an ancillary ligand; k′ is aninteger value from 1 to the maximum number of ligands that may beattached to the metal; and k′+k″ is the maximum number of ligands thatmay be attached to the metal.

In one aspect, (Y¹⁰¹-Y¹⁰²) is a 2-phenylpyridine derivative. In anotheraspect, (Y¹⁰¹-Y¹⁰²) is a carbene ligand. In another aspect, Met isselected from Ir, Pt, Os, and Zn. In a further aspect, the metal complexhas a smallest oxidation potential in solution vs. Fc⁺/Fc couple lessthan about 0.6 V.

Non-limiting examples of the HIL and HTL materials that may be used inan OLED in combination with materials disclosed herein are exemplifiedbelow together with references that disclose those materials:CN102702075, DE102012005215, EP01624500, EP01698613, EP01806334,EP01930964, EP01972613, EP01997799, EP02011790, EP02055700, EP02055701,EP1725079, EP2085382, EP2660300, EP650955, JP07-073529, JP2005112765,JP2007091719, JP2008021687, JP2014-009196, KR20110088898, KR20130077473,TW201139402, U.S. Ser. No. 06/517,957, US20020158242, US20030162053,US20050123751, US20060182993, US20060240279, US20070145888,US20070181874, US20070278938, US20080014464, US20080091025,US20080106190, US20080124572, US20080145707, US20080220265,US20080233434, US20080303417, US2008107919, US20090115320,US20090167161, US2009066235, US2011007385, US20110163302, US2011240968,US2011278551, US2012205642, US2013241401, US20140117329, US2014183517,U.S. Pat. Nos. 5,061,569, 5,639,914, WO05075451, WO07125714, WO08023550,WO08023759, WO2009145016, WO2010061824, WO2011075644, WO2012177006,WO2013018530, WO2013039073, WO2013087142, WO2013118812, WO2013120577,WO2013157367, WO2013175747, WO2014002873, WO2014015935, WO2014015937,WO2014030872, WO2014030921, WO2014034791, WO2014104514, WO2014157018,

EBL:

An electron blocking layer (EBL) may be used to reduce the number ofelectrons and/or excitons that leave the emissive layer. The presence ofsuch a blocking layer in a device may result in substantially higherefficiencies, and or longer lifetime, as compared to a similar devicelacking a blocking layer. Also, a blocking layer may be used to confineemission to a desired region of an OLED. In some embodiments, the EBLmaterial has a higher LUMO (closer to the vacuum level) and/or highertriplet energy than the emitter closest to the EBL interface. In someembodiments, the EBL material has a higher LUMO (closer to the vacuumlevel) and or higher triplet energy than one or more of the hostsclosest to the EBL interface. In one aspect, the compound used in EBLcontains the same molecule or the same functional groups used as one ofthe hosts described below.

Additional Hosts:

The light emitting layer of the organic EL device of the presentinvention preferably contains at least a metal complex as light emittingdopant material, and may contain one or more additional host materialsusing the metal complex as a dopant material. Examples of the hostmaterial are not particularly limited, and any metal complexes ororganic compounds may be used as long as the triplet energy of the hostis larger than that of the dopant. Any host material may be used withany dopant so long as the triplet criteria is satisfied.

Examples of metal complexes used as host are preferred to have thefollowing general formula:

wherein Met is a metal; (Y¹⁰³-Y¹⁰⁴) is a bidentate ligand, Y¹⁰³ and Y¹⁰⁴are independently selected from C, N, O, P, and S; L¹⁰¹ is an anotherligand; k′ is an integer value from 1 to the maximum number of ligandsthat may be attached to the metal; and k′+k″ is the maximum number ofligands that may be attached to the metal.

In one aspect, the metal complexes are:

wherein (O—N) is a bidentate ligand, having metal coordinated to atoms Oand N.

In another aspect, Met is selected from Ir and Pt. In a further aspect,(Y¹⁰³-Y¹⁰⁴) is a carbene ligand.

Examples of other organic compounds used as additional host are selectedfrom the group consisting of aromatic hydrocarbon cyclic compounds suchas benzene, biphenyl, triphenyl, triphenylene, naphthalene, anthracene,phenalene, phenanthrene, fluorene, pyrene, chrysene, perylene, azulene;group consisting aromatic heterocyclic compounds such asdibenzothiophene, dibenzofuran, dibenzoselenophene, furan, thiophene,benzofuran, benzothiophene, benzoselenophene, carbazole,indolocarbazole, pyridylindole, pyrrolodipyridine, pyrazole, imidazole,triazole, oxazole, thiazole, oxadiazole, oxatriazole, dioxazole,thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine,oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole,indoxazine, benzoxazole, benzisoxazole, benzothiazole, quinoline,isoquinoline, cinnoline, quinazoline, quinoxaline, naphthyridine,phthalazine, pteridine, xanthene, acridine, phenazine, phenothiazine,phenoxazine, benzofuropyridine, furodipyridine, benzothienopyridine,thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine;and group consisting 2 to 10 cyclic structural units which are groups ofthe same type or different types selected from the aromatic hydrocarboncyclic group and the aromatic heterocyclic group and are bonded to eachother directly or via at least one of oxygen atom, nitrogen atom, sulfuratom, silicon atom, phosphorus atom, boron atom, chain structural unitand the aliphatic cyclic group. Wherein each group is furthersubstituted by a substituent selected from the group consisting ofhydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl,alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl,alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester,nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, andcombinations thereof.

In one aspect, host compound contains at least one of the followinggroups in the molecule:

wherein R¹⁰¹ to R¹⁰⁷ is independently selected from the group consistingof hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl,arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl,heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylicacids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl,phosphino, and combinations thereof, when it is aryl or heteroaryl, ithas the similar definition as Ar's mentioned above. k is an integer from0 to 20 or 1 to 20; k″ is an integer from 0 to 20. X¹⁰¹ to X¹⁰⁸ isselected from C (including CH) or N. Z¹⁰¹ and Z¹⁰² is selected fromNR¹⁰¹, O, or S.

Non-limiting examples of the additional host materials that may be usedin an OLED in combination with the host compound disclosed herein areexemplified below together with references that disclose thosematerials: EP2034538, EP2034538A, EP2757608, JP2007254297,KR20100079458, KR20120088644, KR20120129733, KR20130115564, TW201329200,US20030175553, US20050238919, US20060280965, US20090017330,US20090030202, US20090167162, US20090302743, US20090309488,US20100012931, US20100084966, US20100187984, US2010187984, US2012075273,US2012126221, US2013009543, US2013105787, US2013175519, US2014001446,US20140183503, US20140225088, US2014034914, U.S. Pat. No. 7,154,114,WO2001039234, WO2004093207, WO2005014551, WO2005089025, WO2006072002,WO2006114966, WO2007063754, WO2008056746, WO2009003898, WO2009021126,WO2009063833, WO2009066778, WO2009066779, WO2009086028, WO2010056066,WO2010107244, WO2011081423, WO2011081431, WO2011086863, WO2012128298,WO2012133644, WO2012133649, WO2013024872, WO2013035275, WO2013081315,WO2013191404, WO2014142472,

Emitter:

An emitter example is not particularly limited, and any compound may beused as long as the compound is typically used as an emitter material.Examples of suitable emitter materials include, but are not limited to,compounds which can produce emissions via phosphorescence, fluorescence,thermally activated delayed fluorescence, i.e., TADF (also referred toas E-type delayed fluorescence), triplet-triplet annihilation, orcombinations of these processes.

Non-limiting examples of the emitter materials that may be used in anOLED in combination with materials disclosed herein are exemplifiedbelow together with references that disclose those materials:CN103694277, CN1696137, EB01238981, EP01239526, EP01961743, EP1239526,EP1244155, EP1642951, EP1647554, EP1841834, EP1841834B, EP2062907,EP2730583, JP2012074444, JP2013110263, JP4478555, KR1020090133652,KR20120032054, KR20130043460, TW201332980, U.S. Ser. No. 06/699,599,U.S. Ser. No. 06/916,554, US20010019782, US20020034656, US20030068526,US20030072964, US20030138657, US20050123788, US20050244673,US2005123791, US2005260449, US20060008670, US20060065890, US20060127696,US20060134459, US20060134462, US20060202194, US20060251923,US20070034863, US20070087321, US20070103060, US20070111026,US20070190359, US20070231600, US2007034863, US2007104979, US2007104980,US2007138437, US2007224450, US2007278936, US20080020237, US20080233410,US20080261076, US20080297033, US200805851, US2008161567, US2008210930,US20090039776, US20090108737, US20090115322, US20090179555,US2009085476, US2009104472, US20100090591, US20100148663, US20100244004,US20100295032, US2010102716, US2010105902, US2010244004, US2010270916,US20110057559, US20110108822, US20110204333, US2011215710, US2011227049,US2011285275, US2012292601, US20130146848, US2013033172, US2013165653,US2013181190, US2013334521, US20140246656, US2014103305, U.S. Pat. Nos.6,303,238, 6,413,656, 6,653,654, 6,670,645, 6,687,266, 6,835,469,6,921,915, 7,279,704, 7,332,232, 7,378,162, 7,534,505, 7,675,228,7,728,137, 7,740,957, 7,759,489, 7,951,947, 8,067,099, 8,592,586,8,871,361, WO06081973, WO06121811, WO07018067, WO07108362, WO07115970,WO07115981, WO08035571, WO2002015645, WO2003040257, WO2005019373,WO2006056418, WO2008054584, WO2008078800, WO2008096609, WO2008101842,WO2009000673, WO2009050281, WO2009100991, WO2010028151, WO2010054731,WO2010086089, WO2010118029, WO2011044988, WO2011051404, WO2011107491,WO2012020327, WO2012163471, WO2013094620, WO2013107487, WO2013174471,WO2014007565, WO2014008982, WO2014023377, WO2014024131, WO2014031977,WO2014038456, WO2014112450,

HBL:

A hole blocking layer (HBL) may be used to reduce the number of holesand/or excitons that leave the emissive layer. The presence of such ablocking layer in a device may result in substantially higherefficiencies and/or longer lifetime as compared to a similar devicelacking a blocking layer. Also, a blocking layer may be used to confineemission to a desired region of an OLED. In some embodiments, the HBLmaterial has a lower HOMO (further from the vacuum level) and or highertriplet energy than the emitter closest to the HBL interface. In someembodiments, the HBL material has a lower HOMO (further from the vacuumlevel) and or higher triplet energy than one or more of the hostsclosest to the HBL interface.

In one aspect, compound used in HBL contains the same molecule or thesame functional groups used as host described above.

In another aspect, compound used in HBL contains at least one of thefollowing groups in the molecule:

wherein k is an integer from 1 to 20; L¹⁰¹ is an another ligand, k′ isan integer from 1 to 3.ETL:

Electron transport layer (ETL) may include a material capable oftransporting electrons. Electron transport layer may be intrinsic(undoped), or doped. Doping may be used to enhance conductivity.Examples of the ETL material are not particularly limited, and any metalcomplexes or organic compounds may be used as long as they are typicallyused to transport electrons.

In one aspect, compound used in ETL contains at least one of thefollowing groups in the molecule:

wherein R¹⁰¹ is selected from the group consisting of hydrogen,deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy,aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl,aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof, when it is aryl or heteroaryl, it has the similar definition asAr's mentioned above. Ar¹ to Ar³ has the similar definition as Ar'smentioned above. k is an integer from 1 to 20. X¹⁰¹ to X¹⁰⁸ is selectedfrom C (including CH) or N.

In another aspect, the metal complexes used in ETL include, but are notlimited to the following general formula:

wherein (O—N) or (N—N) is a bidentate ligand, having metal coordinatedto atoms O, N or N, N; L¹⁰¹ is another ligand; k′ is an integer valuefrom 1 to the maximum number of ligands that may be attached to themetal.

Non-limiting examples of the ETL materials that may be used in an OLEDin combination with materials disclosed herein are exemplified belowtogether with references that disclose those materials: CN103508940,EP01602648, EP01734038, EP01956007, JP2004-022334, JP2005149918,JP2005-268199, KR0117693, KR20130108183, US20040036077, US20070104977,US2007018155, US20090101870, US20090115316, US20090140637,US20090179554, US2009218940, US2010108990, US2011156017, US2011210320,US2012193612, US2012214993, US2014014925, US2014014927, US20140284580,U.S. Pat. Nos. 6,656,612, 8,415,031, WO2003060956, WO2007111263,WO2009148269, WO2010067894, WO2010072300, WO2011074770, WO2011105373,WO2013079217, WO2013145667, WO2013180376, WO2014104499, WO2014104535,

Charge Generation Layer (CGL)

In tandem or stacked OLEDs, the CGL plays an essential role in theperformance, which is composed of an n-doped layer and a p-doped layerfor injection of electrons and holes, respectively. Electrons and holesare supplied from the CGL and electrodes. The consumed electrons andholes in the CGL are refilled by the electrons and holes injected fromthe cathode and anode, respectively; then, the bipolar currents reach asteady state gradually. Typical CGL materials include n and pconductivity dopants used in the transport layers.

In any above-mentioned compounds used in each layer of the OLED device,the hydrogen atoms can be partially or fully deuterated. Thus, anyspecifically listed substituent, such as, without limitation, methyl,phenyl, pyridyl, etc. encompasses undeuterated, partially deuterated,and fully deuterated versions thereof. Similarly, classes ofsubstituents such as, without limitation, alkyl, aryl, cycloalkyl,heteroaryl, etc. also encompass undeuterated, partially deuterated, andfully deuterated versions thereof.

It is understood that the various embodiments described herein are byway of example only, and are not intended to limit the scope of theinvention. For example, many of the materials and structures describedherein may be substituted with other materials and structures withoutdeviating from the spirit of the invention. The present invention asclaimed may therefore include variations from the particular examplesand preferred embodiments described herein, as will be apparent to oneof skill in the art. It is understood that various theories as to whythe invention works are not intended to be limiting.

The invention claimed is:
 1. A compound having a formula selected from

wherein R¹, R², R⁶, and R⁷ each independently represent mono, di, tri,or tetra substitution, or no substitution; wherein R³ represents mono,or di substitution, or no substitution; wherein R⁵ represents mono, di,tri, tetra, or penta substitution, or no substitution; wherein two of X¹to X⁴ are carbon, and the other two are nitrogen; wherein L is a directbond or an organic linker; wherein each R¹, R², R³, R⁴, R⁵, R⁶, and R⁷are independently selected from the group consisting of hydrogen,deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy,aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl,aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof, with the proviso that when the compound has a structure ofFormula D, one of the following is true: (i) R⁴ is not phenyl orsubstituted or unsubstituted quinazoline, (ii) at least one R⁵ or R⁶ isother than hydrogen or phenyl, (iii) L is not a direct bond or phenyl,or (iv) a combination of condition (i), condition (ii), and condition(iii); wherein adjacent substituents of R³ cannot be joined or fusedinto a ring; and wherein any adjacent substituents of R¹, R², R⁴, R⁵,R⁶, and R⁷ are optionally joined or fused into a ring.
 2. The compoundof claim 1, wherein each R¹, R², R³, R⁴, R⁵, R⁶, and R⁷ is independentlyselected from the group consisting of aryl, substituted aryl,heteroaryl, and substituted heteroaryl.
 3. The compound of claim 1,wherein L is a direct bond.
 4. The compound of claim 1, wherein L is anorganic linker selected from the group consisting of aryl, substitutedaryl, heteroaryl, substituted heteroaryl, amino, silyl, and combinationthereof.
 5. The compound of claim 1, wherein R¹, R², and R³ arehydrogen.
 6. An organic light emitting device (OLED) comprising: ananode; a cathode; and an organic layer, disposed between the anode andthe cathode, comprising a compound having a formula selected from

wherein R¹, R², R⁶, and R⁷ each independently represent mono, di, tri,or tetra substitution, or no substitution; wherein R³ represents mono,or di substitution, or no substitution; wherein R⁵ represents mono, di,tri, tetra, or penta substitution, or no substitution; wherein two of X¹to X⁴ are carbon, and the other two are nitrogen; wherein L is a directbond or an organic linker; wherein each R¹, R², R³, R⁴, R⁵, R⁶, and R⁷are independently selected from the group consisting of hydrogen,deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy,aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl,aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof, with the proviso that when the compound has a structure ofFormula D, one of the following is true: (i) R⁴ is not phenyl orsubstituted or unsubstituted quinazoline, (ii) at least one R⁵ or R⁶ isother than hydrogen or phenyl, (iii) L is not a direct bond or phenyl,or (iv) a combination of condition (i), condition (ii), and condition(iii); wherein adjacent substituents of R³ cannot be joined or fusedinto a ring; and wherein any adjacent substituents of R¹, R², R⁴, R⁵,R⁶, and R⁷ are optionally joined or fused into a ring.
 7. The OLED ofclaim 6, wherein the organic layer is an emissive layer and the compoundof Formula A or Formula D is a host.
 8. The OLED of claim 6, wherein theorganic layer further comprises a phosphorescent emissive dopant;wherein the emissive dopant is a transition metal complex having atleast one ligand or part of the ligand if the ligand is more thanbidentate, selected from the group consisting of:

wherein each X¹ to X¹³ are independently selected from the groupconsisting of carbon and nitrogen; wherein X is selected from the groupconsisting of BR′, NR′, PR′, O, S, Se, C═O, S═O, SO₂, CR′R″, SiR′R″, andGeR′R″; wherein R′ and R″ are optionally fused or joined to form a ring;wherein each R_(a), R_(b), R_(c), and R_(d) may represent from monosubstitution to the possible maximum number of substitution, or nosubstitution; wherein R′, R″, R_(a), R_(b), R_(c), and R_(d) are eachindependently selected from the group consisting of hydrogen, deuterium,halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy,amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl,heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof; and wherein any two adjacent substituents of R_(a), R_(b),R_(c), and R_(d) are optionally fused or joined to form a ring or form amultidentate ligand.
 9. The OLED of claim 6, wherein the organic layeris a charge carrier blocking layer and the compound of Formula A orFormula D is a charge carrier blocking material in the organic layer.10. The OLED of claim 6, wherein the organic layer is a charge carriertransporting layer and the compound of Formula A or Formula D is acharge carrier transporting material in the organic layer.
 11. The OLEDof claim 6, wherein the organic layer is an emissive layer and thecompound of Formula A or Formula D is an emitter.
 12. The OLED of claim11, wherein the OLED emits a luminescent radiation at room temperaturewhen a voltage is applied across the organic light emitting device, andwherein the luminescent radiation comprises a delayed fluorescenceprocess.
 13. The OLED of claim 11, wherein the emissive layer furthercomprises a host material and a first phosphorescent emitting material.14. The OLED of claim 13, wherein the emissive layer further comprises asecond phosphorescent emitting material.
 15. The OLED of claim 13,wherein the OLED emits a white light at room temperature when a voltageis applied across the organic light emitting device.
 16. The OLED ofclaim 15, wherein the compound comprising a structure according toFormula A or Formula D emits a blue light with a peak wavelength ofabout 400 nm to about 500 nm or a yellow light with a peak wavelength ofabout 530 nm to about 580 nm.
 17. A consumer product comprising anorganic light-emitting device comprising: an anode; a cathode; and anorganic layer, disposed between the anode and the cathode, comprising acompound having a formula selected from

wherein R¹, R², R⁶, and R⁷ each independently represent mono, di, tri,or tetra substitution, or no substitution; wherein R³ represents mono,or di substitution, or no substitution; wherein R⁵ represents mono, di,tri, tetra, or penta substitution, or no substitution; wherein two of X¹to X⁴ are carbon, and the other two are nitrogen; wherein L is a directbond or an organic linker; wherein each R¹, R², R³, R⁴, R⁵, R⁶, and R⁷are independently selected from the group consisting of hydrogen,deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy,aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl,aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof, with the proviso that when the compound has a structure ofFormula D, one of the following is true: (i) R⁴ is not phenyl orsubstituted or unsubstituted quinazoline, (ii) at least one R⁵ or R⁶ isother than hydrogen or phenyl, (iii) L is not a direct bond or phenyl,or (iv) a combination of condition (i), condition (ii), and condition(iii); wherein adjacent substituents of R³ cannot be joined or fusedinto a ring; and wherein any adjacent substituents of R¹, R², R⁴, R⁵,R⁶, and R⁷ are optionally joined or fused into a ring.
 18. The consumerproduct of claim 17, wherein the consumer product is selected from thegroup consisting of flat panel displays, computer monitors, medicalmonitors, televisions, billboards, lights for interior or exteriorillumination and/or signaling, heads-up displays, fully or partiallytransparent displays, flexible displays, laser printers, telephones,mobile phones, tablets, phablets, personal digital assistants (PDAs),wearable devices, laptop computers, digital cameras, camcorders,viewfinders, micro-displays, 3-D displays, virtual reality or augmentedreality displays, vehicles, video walls comprising multiple displaystiled together, theater or stadium screen, and a sign.
 19. A formulationcomprising a compound of claim
 1. 20. The compound of claim 1, whereinthe compound is selected from the group consisting of: